6-TET phosphoramidite [5-Tetrachlorofluorescein phosphoramidite]

There are several ways of labeling an oligonucleotide with fluorescein. The choice of label is diversified further, depending on the spectral requirements. 5-fluorescein-CE phosphoramidite, derived from the single isomer 6-carboxyfluorescein, 5-hexachlorofluorescein-CE phosphoramidite (HEX) and 5-tetrachlorofluorescein-CE phosphoramidite (TET) can all be used to efficiently label an oligonucleotide at the 5-end. Labeling the 3-end of an oligo with fluorescein can be achieved using 3-Fluorescein CPGs. Standard cleavage and deprotection with ammonium hydroxide liberates the fluorescein-labeled oligo when using any of these supports.